The present invention relates generally to provision of scaffolds for construction purposes and more specifically to motorized scaffold hoisting apparatus for use in general construction work on buildings.
A scaffold is defined as a temporary or movable platform (e.g., a wooden or metal plank) that is supported from below by one or more suitable devices such as a stationary framework or jacks on poles, or suspended from above using rope and tackle or a roof-mounted hoist. Scaffolds are used for supporting workers and also materials of construction such as shingles, bricks, and painting materials. Most scaffolds used for working on two or three story buildings are supported by rope and tackle devices or by jacks on poles. Pole jacks are more convenient to use, but they are more costly. The prior art relating to pole jacks, and poles specially designed for use with pole jacks ("jack poles"), is exemplified by U.S. Pat. Nos. 4,382,488; 4,223,507; 5,042,615; 4,805,735; 4,598,794; 4,597,471; and 5,259,478.
There have been prior efforts to provide motor-powered scaffold hoists for construction work on two and three story buildings, but such efforts have achieved little or no success. Size, cost, adequate fail-safe operation and ease of installation and use are critical factors affecting commercial success.